In the field of power management, distribution of available power to different loads is a critical exercise. The power demand and power supply mismatch leads to ineffective load scheduling and situations of unscheduled power cuts for several hours to reduce the peak demand at a particular time interval during a day. The power demands by different power users, like commercial and residential users in cities, agricultural, residential users in rural areas, industrial users, are different and for proper power management their different power demands have to be addressed and effectively managed.
The power system comprises of one or more of generation system, transmission system and distribution system. The power generated is usually stepped-up and transmitted through the transmission system, and at the distribution end, one or more substation systems along with the low voltage or medium voltage distribution network, distribute power to the users. For distribution, the power system has numerous automation products e.g. products for substation management/automation performing power balance and load shedding, distribution network management system for optimally distributing the power in the distribution network etc. In the context of this invention, a distribution management system (DMS) is defined for managing power distribution to the users and the scope of such a distribution system includes substation as well as distribution networks management systems. Further, the distribution management system (DMS) is also referred to as power distribution management system (PDMS).
In some cases, a dedicated feeder may be utilized for a class of loads (e.g. irrigation loads) and these may be well separated from the other feeders allowing greater flexibility in power management. As the demand for power is constantly increasing with a need to include and service more and more number of loads, the capacity of such a feeder or the equipments in the distribution network may become a constrain, requiring scheduling of loads also within a particular feeder system to ensure good utilization of the infrastructure and provide effective service to all.
In some situations the power for agricultural needs are also supplied by the same feeder delivering power for residential needs, particularly in rural or remote locations and hence, there may be interactions leading to overloading of the distribution network or affect of load shedding. For example, in rural areas, in some developing countries power cut-off exists for 10-12 hrs to accommodate power demand of other loads. In such a situation, farmers are inclined to run the irrigation pump sets beyond the stipulated hours for saving their crops with the season coming to a close and with the water-table falling at some places. Several irrigation pumps in a certain zone may draw power at the same time which results in over-loading of the power system. This causes a cascading effect and leads to a sudden increase of power demand steeply, which in turn results in more power cuts in rural areas. There may be several other non-efficient ways that a deprived power user may resort to in order to some-how get electricity. For example, evening hours in rural areas are supplied with single phase power. The farmers use converters that allow pumpsets to operate on single-phase power that result in frequent pump burnout because of high currents. Due to frequency of pump burnout, farmers rely on use of locally manufactured pump which are categorized as inefficient pumps, instead of standard certified pumps drawing more power and causing further imbalance in distribution network, overloading of the distribution transformer, and hence degradation of quality of power supply.
Similar situations are there for each segment of power users like residential, commercial, and industrial users.
The power management system operating at distribution level often transfers a load from one feeder to another to optimally utilize the capacity in the various sections of the distribution network and have a good balance of the loads in the various sections of the distribution network. However, today power management system at distribution level does not influence or does not consider the dynamic conditions of loads that are connected either automatically (includes loads that are systematically operated based on a schedule) or switched manually (operated in ad-hoc manner) in its calculation for load balanced state or configuration of loads.
In some of the current approaches for power demand management, for example, in the irrigation sector, local control systems are used that take inputs of soil condition to generate a schedule for the associated irrigation pump. The different irrigation pumps are assigned priorities and based on power demand and available capacity the power distribution is done according to prioritized schedules. In another approach, some devices are selected as controlled devices, and energy consumed by such devices like a refrigerator, electric water heater, well pumps, is measured, and during peak load times, energy to such devices is cut off and the consumer is given a rebate based on energy saved. None of these approaches provide an integrated solution of optimizing load schedules and optimizing a match between power demand and available power at the power distribution level.
Therefore there is a need for a technique that will enable optimal load scheduling integrated within the power distribution management systems, so that the power demand for any segment of power user is effectively managed.